The invention is based on a fuel injection pump in accordance with the type of the main claim.
In a known fuel injection pump of this type (Bosch distributor injection pump VE Bosch technical instruction VDT-u 2/2 De) the injection adjustment bolt is secured against axial displacement by a pin which transversely penetrates the injection adjustment piston immersing into a bore of the drive ring, whereby the pin is protected against dropping out by means of a steel clamp which encompasses the injection adjustment piston.
This known type of axial securing of the injection adjustment piston is disadvantageous in that after inserting the bolt during assembly of the injection pump one must mount the safety pin and the clamp requiring two operating steps, whereby the injection adjustment piston must be brought into the turning position in which the bore receiving the safety pin is in a superimposed position with the associated bore in the drive ring. Moreover, each additional operating step or each additional structural part, like the safety pin and the sheet metal clamp, disadvantageously require an additional manufacturing control irrespective of the additional material and finishing expenses for these parts. Since such fuel injection pumps are made in great numbers, the aforementioned disadvantages are accordingly serious.
A substantial disadvantage of this known fixing of the injection adjustment bolt consists in that the injection adjustment bolt is prevented from rotating around its own axis because of the safety pin. Thereby, engagement faces develop one sided wear with respect to the drive ring and with respect to the injection adjustment piston due to the stress. Thus, when running, wear deviations result from the actual value to the rated value of the start of the feeding, which may result in a critical running or even a damaging of the internal combustion engine which is supplied by the injection pump.